1. Z. S. Artem’eva, Organic Matter and Particle-Size System of Soil (GEOS, Moscow, 2010) [in Russian].
2. A. A. Aseev and A. G. Doskach, “Geomorphic regioning,” in Plains of the European Part of the Soviet Union (Nauka, Moscow, 1974), pp. 225–235 [in Russian].
3. A. Ya. Vanyushina and L. S. Travnikova, “Organic-Mineral Interactions in Soils: A Review,” Eur. Soil Sci. 36(4), 379–387 (2003).
4. M. A. Vinokurov and P. V. Grishin, Forest Soils of Tataria (Izd. KGU, Kazan, 1962) [in Russian].
5. A. Kh. Gazizullin, Forest Soils of the Kama Reaches in the Tatar Autonomous Republic and Their Rational Use, Cand Sci. (Biol.) Diss. (Ioshkar-Ola, 1972) [in Russian].